Pyrochlore flotation

ABSTRACT

An ore containing small amounts of columbium-bearing minerals is beneficiated by froth flotation, an aqueous pulp of the ground ore being floated in the presence of a cationic collector of the amine type, a surface active agent and a modifying agent providing a source of free oxalate ions from the group consisting of oxalic acid and oxalate salts. A concentrate rich in the columbium-bearing minerals is floated off and collected, with a columbium-lean tailing remaining.

United States Patent 1191 Raby et al. Oct. 7, 1975 PYROCHLORE FLOTATION 2,861,687 11/1958 Lord 209/166 x 2,875,896 3/[959 Last 209/166 [75] Inventors Raymmd Raby Clement 2,951,585 9/1960 Burks 209 167 Desmchers, both of y 2,959,281 11/1960 Faucher 209/166 x Canada 3,014,585 12/1961 NOblltt 209/166 x [73] Assignee: Soquem, Montreal, Canada (flu- PUBLICATIONS [22] Filed: July 29, 1974 Chem. Abst,, Vol. 69, 1968, 986041;.

A NOJ 492 704 Chem. AbSL, VOl. 69, 1968, 10883lk.

Related Application Data Primary Examiner-Robert Halper [63] Continuation-impart of Ser. N6 311,282, Dec. 1,

1972, abandoned. ABSTRACT [30] Foreign Application Priority Data An ore containing small amounts of columbium- Jan. 29, 1972 United Kingdom 4307/72 bearing mineralg is beneficiated by froth flotation an aqueous pulp of the ground ore being floated in the 52 US. Cl 209/166; 209/12 Presence a cationic collect of the amine type, a 51 Int. (:1. B03D 1/02 Surface active agent and a modifying agent Providing a [58] Field of Search 2097166, 167 2, 12, 3 source of free oxalate ions from the group consisting of oxalic acid and oxalate salts. A concentrate rich in [56] References Cited the columbium-bearing minerals is floated off and col- UNITED STATES PATENTS lected, w1th a columblum-lean ta1l1ng remammg.

1,912,434 6/1933 Crago 209/166 8 C a m 2 Draw ng Figures ave/mama anssmcnnavsum-s alt/0M: (macro/r COAID/f/O/V/NG M MID IAOFS/Ml/C 11cm c RETIFEATMLWT 'fggjz fi REJECTS l chi/ow: muscran moor/Mas cb gczmmm/a amt/cum 'MO/PGAA/IC 4:10

(Al/Sl'lC/ZED sm/Pa/ caA/o/r/oM/va sop/0M smurf muss/0M nun XAA/f/Mf' 1 FIR/r! FIR/7E awn: FLOIAf/Oll/ c0/1/c://m4r 1 a 1 ,u/apuvas AETRiAfMA-W? DESl/MM/G i 1 sumss 1 arm/w: cauzcron MIDDl/NGS fb gtliflflllfi 4 Zjjgfigjjj, 5mm

JOB/(1M 5/2 xcms PYROCHLORE FLOTATION This is a continuation-in-part of application Ser. No. 31 1,282, now abandoned filed Dec. 1, 1972.

BACKGROUND OF THE INVENTION This invention relates to the beneficiation by froth flotation of columbium-bearing minerals from ore containing such minerals. It is particularly applicable to those columbium (niobium) ores containing various proportions of carbonates, such as dolomite, calcite, etc.;1 silicates such as mica, pyroxene etc., and metallic oxides such as ilmenite, hematite, magnetite etc., and other minerals such as apatite, zircon, sulfides, etc.

The invention is most useful in the treatment of ores containing pyrochlore, such as the pyrochlore-bearing ores found in the province of Quebec, Canada, which contain large quantities of gangue materials, including large quantities of carbonates. I

There are few processes available for effectively and economically obtaining concentrates of columbium minerals from columbium-bearing ores which are rich enough in columbium content to be commercially useful. In U.S. Pat. No. 2,875,896 columbium minerals are concentrated by froth flotation using a reagent from the hydroxy quinoline group of chemical compounds as a selective collector for columbium minerals. US. Pat. No. 2,951,585 discloses a separation of pyrochlore from calcite, apatite and silica by froth flotation in the presence of an aliphatic monoamine or diamine and an improvement in this process is advanced in US. Pat. No. 3,014,585 by use of a modifying agent consisting of a water-soluble bicarbonate in the flotation solution. Unfortunately, none of these processes result in a high grade Cb O concentrate.

In US. Pat. No. 2,959,281 a process is disclosed whereby columbium-bearing ores are beneficiated by froth flotation using a cationic promoter of the amine type and a selective activator containing a source of free fluoride and fluosilicate ions.

Russian researches have made unsuccessful efforts to produce suitable pyrochlore concentrates and have used what is referred to as an lM-SO complexing reagent in association with oxalic acid and sodium silicate. The lM-SO reagent is obtained by synthesizing higher alkylhydroxamic acids. The Russian mining industry has, however, been forced to resort to chemical processing to produce a columbium product which can be sold on the world market.

It has now been found that columbium-bearing minerals, and particularly'those of the pyrochlore type, can be floated from alkaline ores, with a good separation from the gangue constituents utilizing a novel reagent combination comprising a cationic collector of the amine or diamine type emulsified with a surface active agent and a modifying agent, providing a source of free oxalate ions, from the group consisting of oxalic acid and oxalate salts, with or without pH modifier, including any inorganic acid, in an acid circuit.

SUMMARY In the process of the invention a low grade ore containing small amounts of columbium-bearing minerals, and in particular pyrochlore, associated with large amounts of gangue, including large quantities of carbonates, is first ground to aparticle size suitable for separation of the columbium-bearing minerals by froth flotation and an aqueous pulp of the finely ground ore is then subjected to froth flotation in'the presence of a cationic collector of the amine type, and particularly of the diamine acetate type, advantageously having a carbon chain length of 10 to 22 carbon atoms, a dispersing agent and a modifying agent providing a source of free oxalate ions from the group consisting of axalic acid and oxalate salts to obtain a concentrate rich in the columbium-bearing minerals and a columbium-lean flotation tailing. Inorganic acids such as hydrochloric, sulfuric and phosphoric are useful in maintaining an acid circuit and gangue depressants such as caustic starch, sodium silicate and lactic acid may be used in the circuit. Furthermore, the addition'of CaCl can be beneficial to the circuit.

The principal object of the present invention is to provide an improved process for the flotation of columbium-bearing minerals from alkaline ores (carbonatites) by which a high grade Cb O concentrate can be obtained.

Other objects and advantages of the invention will be apparent from the description following taken in conjunction with the accompanying drawing in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a flowsheet of a process embodying the invention; and

FIG. 2 is another flowsheet illustrating a further embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I of the drawings and, for illustrative purposes referring to flotation of a pyrochlore concentrate, the ore is crushed and ground to a fineness of -65 mesh and a pulp of the ground ore is deslimed and then conditioned with a cationic collector of the diamine acetate type, and a dispersing agent acting in combination with the collector together with oxalic acid or an oxalate salt. The conditioned pulp is submitted to flotation to obtain a rougher pyrochloric concentrate which is cleaned using the same reagents in a number of cleaning stages. Middlings from such cleaning are re-treated and returned to the rougher flotation step.

The cleaned pyrochlore concentrate is submitted to a sulfide flotation, where necessary, after conditioning with caustic starch and/or sodium silicate'along with a suitable xanthate collector, such as potassium amyl xanthate, to obtain a rougher pyrite concentrate which is cleaned, with the cleaner middlings being returned to the pyrochlore concentrate. A second desliming of the pyrochlore concentrate may advantageously be carried out and it is then submitted to further cleaning stages while using the cationic collector, as before, oxalic acid and a gangue depressant. Middlings are returned to the pyrochlore rougher flotation and a high grade Cb O flotation concentrate is obtained containing as high as 65% Cb O It is possible also to 'carry out reverse flotation of the pyrite after the last Cb O cleaning stage.

The process of the invention is embodied also in the procedure illustrated by the flowsheet of FIG. 2 in which carbonates and silicates a're pre-floated followed by the flotation of pyrochlore using oxalic acid. By this procedure the ore is ground to 65 mesh and a pulp of the ground ore in water is deslimed and conditioned with suitable reagents for a carbonate flotation and then subjected to flotation of a rougher carbonate concentrate. This carbonate Concentrate is cleaned using similar reagents and the cleaner tails are combined with the rougher tails for subsequent pyrochlore flotation.

The combined tails are deslimed and conditioned with a suitable cationic collector of the diamine acetate type, and a dispensing agent together with oxalic acid. An inorganic acid may be added for pH control, the flotation process being carried out in an acid medium, i.e. at a pH of below 7. A'Cb O rougher concentrate is floated and this concentrate may, if necessary, be subjected to a sulfide flotation after conditioning with a suitable gangue depressant and a suitable xanthate collector. The pyrite rougher concentrate is advantageously cleaned with the middlings being combined with the pyrite rougher tails (pyrochlore concentrate). The pyrochlore concentrate is submitted to a number of cleaning stages using reagents as in the Cb O rougher flotation and middlings from the cleaning stages are returned to the Cb O rougher flotation. A high grade Cb O concentrate is obtained.

It is to be noted that columbium-bearing ores treated according to the process of the invention contain large quantities of silicates or gangue, such as mica, pyroxene, nepheline, melilite and plagioclase, and, in particular, gangue such as the carbonates dolomite, calcite, ankerite and siderite. Minerals such as apatite, fluoride, zircon, sulfides and barite and heavy minerals such as hematite, magnetite and ilmenite may be present. These silicates or gangue, heavy minerals and carbonates are depressed in the flotation by the combined effects of the oxalic acid and a suitable gangue depressant such as caustic starch, sodium silicate, phosphoric acid and lactic acid. In the process it is not necessary to use separate magnetic or gravity separation to eliminate magnetite, ilmenite, rutile, hematite or mica. Mica can be an abundant gangue material associated with pyrochloric and mica is advantageously depressed during the froth flotation using caustic starch, lactic acid or phosphoric acid. The heavy minerals such as ilmenite, hematite and magnetite are depressed by the same depressants as for mica. Carbonates in the ore, such as for example, dolomite, ankerite, calcite and siderite are advantageously depressed in the flotation by the combined effects of the oxalic acid and a suitable gangue depressant, such as caustic starch or sodium silicate. Part or most of the carbonates may, however, as illustrated in the flowsheet of FIG. 2, be pre-floated before flotation of the columbium-bearing minerals.

Although the embodiments of FIGS. 1 and 2 of the drawings have been described with reference to obtaining a pyrite concentrate when floating sulfides from the pyrochlore concentrate, sulfides other than pyrite may be removed by this flotation operation.

As afore-mentioned, the flotation of the columbiumbearing mineral is carried out in an acid circuit, i.e. at a pH of below 7, and acids such as hydrofluoric, sulfuric, hydrochloric and phosphoric may be used as pH modifiers. Hydrofluoric acid may be mixed with the oxalic acid or oxalate salt modifying agent in the flotation operation. An admixture of up to in the order of equal amounts of hydrofluoric acid with oxalic acid appears to be useful. Furthermore, the addition of calcium chloride to the circuit has been found to have some beneficial effects for the pyrochlore flotation.

It is to be noted that it is the novel combination of the cationic collector of the diamine acetate type together with the oxalic acid or oxalate salt modifying agent which provides the very selective flotation action towards the pyrochlore mineral. Preferably, the diamine acetate collector should be one having a carbon chain length of 10 to 22 carbons or mixtures thereof in order to provide the most effective flotation of the pyrochlore mineral.

The following examples are illustrative of the process of the present invention.

EXAMPLE I Direct Pyrochlore Flotation with Oxalic Acid A sample of pyrochlore-containing ore from the St- Hon'ore district (Chicoutimi) Province of Quebec, Canada, which is associated with dolomite, calcite, apatite, mica, pyroxene, heavy minerals, such as ilmenite, magnetite, hematite and sulfides and normally contains 0.90 to 1.05% Cb O was prepared by crushing and grinding to 65 mesh fineness and was treated in accordance with the flowsheet shown in FIG. 1.

A pulp of the ground ore containing about 35% solids in water was deslimed and conditioned for one minute with 0.90 lbs./ton of a properly prepared mixture of 3 parts and 1 part respectively of Duomac-T (trade mark) and Ethofat 242/25 (trade mark) cationic collectors (both produced by Armour Industrial Chemical Co.) and 1.50 lbs/ton of oxalic acid. The Ethofat 242/25 and Ethofat 242/45, referred to hereinafter, are dispersing agents consisting of ethoxylated fatty acids, as defined by Annour Industrial Chemical Co., and they act in combination with the Duomac-T collector to provide the necessary selectivity for pyrochlore.

The conditioned pulp was then submitted to the flotation of a rougher pyrochlore concentrate which was cleaned five times, while adding the following quantities of reagent at the various cleaning stages:

0.05 to 0.35 lbs/ton 0.25 to 0.50 lbs/ton Duomac-T Ethofat 242/25 Oxalic Acid Duomac-T Ethofat 2.42/45 Oxalic Acid Caustic Starch Sodium Silicate 0.0 to 0.05 lbs/ton 0.25 to 0.50 lbs/ton 0.00 to 0.05 lbs/ton 0.00 to 0.10 lbs/ton The results of this procedure are shown in Table I.

Table No. 1

Products 7: Weight 7: Cb O 7n Recovery Slirnes 12.35 0.58 7.9 Rejects 38.40 0.03 1.2

Table No. I-Continued I -Continued Products 7: Weight 71 Cb- O5 7r Recovery Conditioning for Cb O,, Flotation:

Sulfides 0.60 V 0,60 0,4 Duomac-T Ethofat 242/45 0.005 to 0.1 lbs/ton Middlings 52,60 017 15,5 5 Oxalic Acid 0.25 to 0.5 lbs/ton Cbp, concentrate 1.25 54.5 75.0 ghosphoriigcid 0003; :gston y omotor to 5. ton Calculated head 100.00 0.91 100.0 Causticized starch 00 to 010 lbs'lmn Sodium Silicate 0.0 to O. 15 lbs/ton Conditioning for Sulfide Flotation:

AM H 10 Causticized Starch 0.05 lbs/ton Sodium. Silicate 0.1 1bs./ton A sample similar to that used in Example I, was L f g i y treated according to the same procedure except oxalic our ages acid addition was reduced and hydrochloric acid was Duomac-T Ethofat 242/25 0.00 to 0.02 lbs/ton Oxalic Acid 0.15 to 0.25 lbs./ton added. The following quantities of reagents were used. Phosphoric Acid Q00 to 0.05 when Promotor 825 0.00 to 0.02 lbs/ton Causticized Starch 0.00 to 0.05 1bs./ton Sodium Silicate 0.0 to 0.1 lbs/ton Conditioning for Cb O Flotation:

The final concentrate obtained was leached with an gr 'i g gg 242/ excess quantity of 37% concentrated hydrochloric acid Hydrochloric Acid 0.5 lbs/ton to obtain the final product.

FITS Cleanmg Slageg The results of the procedure used in Example III are DUOmuC-T Ethofat 242 45 0.03 to 0.15 lbs/ton 25 Show m Table Oxalic Acid 0.15 to 0.5 lbs/ton Hydrochloric Acid 0.15 to 0.5 lbs./ton Table NO I" Conditioning for Sulfide Flotation:

Products 71 Weight 71 (b- 0,, 7( Distribution Causticized Starch 0.05 lbs/ton Sodium Silicate 0.10 lbs./ton slimes 1 1'5 Q53 7 Potassium Amyl Xanthate 0.02 lbs/ton Rejects 510 009 5.0 Last Four Cleaning Stages: sulfides O 5 049 0.3 Middlings 34.0 0.41 15.7 Duomac-T Ethofat 242/45 0.0 to 0.05 lbs/ton Flot. (b- O; Conc. 2.04 31.6 71,9 Oxalic Acid 0.15 to 0.25 lbs./ton '0] t d H mono 0 90 mo 0 Hydrochloric Acid 0.15 to 0.25 lbs/ton g iggj g com 120 1 Causticiied Starch 0.0 to 0.05 lbs/ton 5 Sodium Silicate 0.0 to 0.10 lbs/ton EXAMPLE IV The final concentrate obtained was leached with an excess quantity of 37% concentrated hydrochloric acid A sample of ore 51mm to h one desFntfed m Exam to Obtain the final product 40 ple I was prepared by crushing and grinding to a 65 The results of the procedure used in Example 11 are meshdfjmeness and was'treated by the Procedure shown in Table [I trate 1n the flowsheet in FIG. 2 by which the carbonates and silicates are pre-floated followed by flotation Table H of the pyrochlore. The pulp formed containing about 35% solids in water was conditioned for 15 minutes Products Weight 2 -i Distribution with 1.25 lbs./ton of causticized starch,. 1.00 lbs/ton of sums '2 0.54 6] sodium silicate l.30 lbs./ton of a fatty acid Lannagol Rejects 4 ,9 0,05 2, (trade mark) emulsion and 0.04 lbs./ton of M.I.B.C. a ga? 3-2 2 (Methyl-Isobutyl-Carbinol). The conditioned pulp was In S c HOL cbiofi Com L68 402 743 so then submitted to the flotation of a rougher carbonate calculated Head 90 1009 concentrate, which was cleaned four times, while re- Leached 2 Conc. 15 turning the cleaner tails with the rougher tails for subsequent pyrochlore flotation.

The following reagents were added at the various car- EXAMPLE I bonate flotation cleaning stages. A sample similar to that used Example I was treated according to the same procedure except oxalic w d a acid was Caustized Starch 0.05 to 1.00 lbs/ton acld addltlon as redu nd Phosphoric Sodium Silicate 0.05 to 1.001bs./ton added. Fatty Acid Lannagol 0.00 to 0.40 lbs/ton 60 Emulsion Conditioning C15 0; Flotation: The carbonate flotation rougher and cleaner tails 'ji t; Ethofm 242/25 07 lhsJum were then deslimed and submitted to rougher pyrooxalic Add 05 [bi/m chlore flotation after a conditioning period of one mm- Phosphoric Acid 0.5 lbs./ton- Ute i h 030 lb t n f D Reagent 825 (Cyanamid) 0.25 lbs/ton o uomdc T Ethofat Emulslon First Five Cleaning Stages:

and 2.20 lbs/ton of oxalic acid. The tailings were rejected and the rougher concentrate was then submitted to sulfide flotation after Conditioning for five minutes with 0.10 1bs./ton of causticized starch, 0.15 lbs/ton of sodium silicate and 0.02 lbs/ton of potassium amyl xanthate.

The pyrite rougher tails (pyrochlore concentrate) was then submitted to four cleaning stages while adding the following reagent at the various cleaning stages:

DuomacT Ethofat 0.00 to 0.05 lbs./ton 0 Oxalic Acid 0.25 to 0.74 lbs./ton Causticized Starch 0.00 to 0.05 lbs/ton Sodium Silicate 0.00 to 0.10 1bs./ton

The results obtained by the procedure of Example IV are shown in Table IV.

Table No. IV

Products "/1 Weight 7: ch 0; 7: Distribution Carbonates Conc. 54.6 0.10 5.4 0

Slimes 3.3 1.50 5.0

Rejects 23.9 0.09 2.0

Pyrite Conc. 0.8 0.17 0.1

Middlings 16.1 0.75 11.6

Flot. ch 0; Conc. 1.3 58.50 75.9

Calculated Head 100.0 1.03 100.0

EXAMPLE V A composite sample similar to that used in Example I was treated according to the same procedure as used in that example except that a mixture of hydrofluoric and oxalic acids in a ration of 1 part HF to 3 oxalic was added and the sulfides were floated off after the seventh Cb O cleaning stage. 3S

Conditioning for Ch- 'O Flotation:

Duomac-T Ethofat 2.42/25 0.85 lbs./ton 4O Acid Mixture 0.05 1bs./ton First Seven Cleaning Stages:

Duomac-T Ethoi'at 242/25 0.02 to 0.35 1bs./ton

Acid Mixture 0.25 to 0.50 1bs./ton

Causticized 0.00 to 0.05 1bs./ton

Sodium Silicate 0.00 to 0.10 lhs./ton Conditioning for Sulfide Flotation:

Causticized Starch 0.05 lbs./ton

Sodium Silicate 0.10 lbs/ton Potassium Amyl Xanthate 0.02 lbs/ton Sodium Hydroxide to alkaline pH Last Cleaning Stage:

Duomac-T Ethol'at 242/25 0.01 lbs/ton Acid mixture 0.50 lbs/ton Causticized Starch 0.05 lbs/ton The results obtained by this procedure are shown in Table V.

Table No. V

Products 71 Weight 71 C b ,O,-, "/r Distribution Slimes 7.7 0.44 3.8 Rejects 88. l 0.08 8.8 Sulfides 0.6 0.43 0.3 Middlings 2.0 1.62 3.6 Flot. Cb O Conc. 1.56 47.7 83.5 5 Calculated Head 100.0 0.89 100.0

EXAMPLE v1 Example V was repeated except that a mixture of hydrofluoric and oxalic acids in a ratio of 1 part HF to 1 part oxalic acid was used. Otherwise, the same procedure and the same reagents were used as in Example V. The results obtained are shown in Table VI.

It has been found that the use of oxalic acid as a modifying agent in the promotion of the flotation of columbiurn-bearing minerals, such as pyrochlore, has an advantage over using hydrofluoric acid as a modifying agent in substantially reducing the amount of silica in the pyrochlore flotation concentrate. A series of tests were conducted illustrating this advantage in which the same procedure and the same reagent materials were used, the ore being treated being the same in each test, except that hydrofluoric acid was used as a modifying agent in five of the tests and oxalic acid was used as a modifying agent in nineteen of the tests. In Table VII the precent Cb O and the percent SiO in the flotation concentrates obtained in each of the tests is given. The results of Table V11 show that a concentrate with substantially the same Cb O content has, on the average, a much lower silica content when using oxalic acid than when using hydrofluoric acid.

As aforementioned, the addition of calcium chloride is found to have some beneficial effects for the pyrochlore flotation as clearly illustrated by Example VII following.

EXAMPLE V11 Two test runs were carried out on the same composite sample similar to that used in Example I. The reagent combination and procedure used were the same as those used in Example I. One run was carried out with- Table No. VIII EXAMPLE VIII The Duomac-C and Duomac-HH collectors were compared with Duomac-T collector in two series of WITHOUT CaCl WITH 10 lbs./ton CaCl ADDITION ADDITION ch I 2 I Wt 7r Cb O Distr. '71 Wt 7t Cb O,-, Distr.

Slimes 8.4 0.55 5.2 8.5 0.48 4.8 Rejects 72.7 0.074 6.1 80.5 0.044 4.2 Pyrite I Concentrate 0.46 0.38 0.2 0.45 0.25 0.1 Middlings 17.0 0.32 6.8 9.3 0.73 8.1 ch 0 Concentration 1.45 50.2 81.7 1.24 56.30 82.8

Feed

Calculated 100.0 0.89 100.0 100.0 0.84 100.0

The cationic collector of the amine type used in combination with the oxalic acid or oxalate salt modifying agent is, as aforementioned, preferably- 0f the diamine acetate type advantageously having a carbon chain length of 10 to 22 carbon atoms. The Duomac-T collector used in the preceding examples has saturated C-16 and C-18 fractions of 29.0 and 23.0% by weight respectively, with smaller amounts of saturated C-12, C-l4, C-l5 and C-17 fractions totalling 5.5%, and an unsaturated fraction totalling 42.5% by weight. This collector provided the most advantageous results of the diamine acetate collectors used. However, other diamine acetate collectors in the C-10 to C-22 group have proven to be effective also in the process of the tests. The first series (Direct) was performed ,following the standarddirect flotation procedure used in Example I and the second series (Carbonate Preflotation) was performed using the carbonate prefloat procedure of Example IV. Reagents and procedures used were as in Examples l and IV, respectively. Each Duomac collector was addd in a mixture containing 3 parts Duomac and 1 part Ethofat 242/25 in a 1% aqueous solution, as in all the previous examples. Results of the two series of flotation tests are summarized in Table X. Tests 2 and 5 were carried out using a mixture of oxalic and hydrofluorici acids as modifying agent in the ratio of 3 parts oxalic to 1 part hydrofluoric as in Example V.

TABLE X TEST FLOTATION MODIFYING COLLECTOR HEADS CONC. RECOV- REAGENT CONSUMPTION LBS/T ERY No. PROCESS AGENT Cb O 71 C13 0; 7r Cb- ,O ColIector Acid 1 Direct Oxalic Duomac T 0.94 55.3 66.0 1.105 4.75

2 Direct Oxalic HF Duomac T 0.93 54.8 67.7 0.855 4.00

3 Direct Oxalic Duomac C 1.03 55.2 55.3 0.97 4.00

4 Carbonate Oxalic Duomac T 0.93 45.5 64.3 0.47 3.50

Preflotation 5 Carbonate Oxalic HF Duomac T 0.90 53.3 70.9 0.30 3.25

Preflotation 6 Carbonate Oxalic Duomac C 1.03 -57.7 51:7 0.47 3.50

Preflotation I 7 Carbonate Oxalic Duomac HH 0.99 42.1 23.94 0.48 3.75

Preflotation Table IX Chain Length Distribution (/1) of Collectors Used in Example VIII (Saturated) Duomac C Duomac T Duomac HH G8 8.0 C-IO 7.0 C-l2 50.0 1.0 C-l4 18.0 3.0 6.1 C-lS 0.5 C-l6 8.0 29.0 28.1 C-l7 1.5 1.0 C-l8 23.0 22.8 C-20 23.0 C-22 19.7 C-24 Unsaturated 7.0 42.5 0

Total The Duomac-T collector is seen by the results of Example VIII to be the most effective of those tested. Thus, the diamine acetate group of collector having a carbon chain length of 16 to 18 carbon atoms is most advantageous. However, the Duomac-C collector, with carbon fractions essentially in the C-l2 to C-14 range, shows excellent selectivity but with lower recovery in .the tests carried out. Less efficiency in terms of selectivity and recovery was found in the Duomac-HH collector having carbon fractions essentially in the C-16 to C-22 range. The tests of Example VIII show, nevertheless, that diamine acetate collectors having different carbon chain length within C-lO to C-22 give reasonable results for pyrochlore flotation, the poorer results obtained with the longer carbon chain collectors being still quite acceptable.

It can be seen that the process of the present invention provides a simple and economical procedure for treating ores containing small amounts of columbiumbearing minerals and large amounts of gangue materials, particularly carbonates, by froth flotation techniques to obtain a high grade Cb O concentrate.

What we claim is: l. A process for beneficiating by froth flotation an ore containing small amounts of the columbiumbearing mineral pyrochlore and large quantities of gangue materials, including large quantities of carbonates from the group comprising dolomite, ankerite, calcite and siderite, which comprises grinding said ore to a small particle size suitable for separation of the columbium-bearing minerals by froth flotation, subjecting an aqueous pulp of the so-ground ore, in the presence of a cationic collector of the diamine acetate type, having a carbon chain length of to 22 carbon atoms, a dispersing agent acting in combination with the collector, a modifying agent providing a source of free oxalate ions from the group consisting of oxalic acid and oxalate salts and at least one depressant from the group consisting of caustic starch and sodium silicate to depress the carbonates in combination with the modifying agent, to froth flotation at a pH of below 7 and forming a concentrate rich in the columbiumbearing minerals and a columbium-lean tailing and collecting said concentrate.

2. A process as claimed in claim 1 wherein the diamine acetate collector has a carbon chain length of in the order of 16 to 18 carbon atoms.

3. A process as claimed in claim 1, wherein calcium chloride is included as a modifying agent in the flotation treatment in promoting the pyrochlore.

4. A process as claimed in claim 1, wherein the gangue materials include heavy minerals from the group comprising ilmenite, hematite and magnetite and .at least one depressant from the group consisting of caustic starch and lactic acid is used to depress the heavy minerals.

5; A process. for beneficiating by froth flotation an ore containing small amounts of the columbiumbearing mineral pyrochlore and large quantities of gangue materials, including large quantities of carbonates, which comprises grinding said ore to a small particle size suitable for separation of the columbiumbearing minerals by froth'flotation, subjecting an aqueous pulp of the so-ground ore, in the presence of a cationic collector of the diamine acetate type, having a carbon chain length of 10 to 22 carbon atoms, a dispersing agent acting in combination with the collector, a modifying agent providing a source of free oxalate ions from the group consisting of oxalic acid and oxalate salts, at least one gangue depressant from the group consisting of caustic starch, sodium silicate and lactic acid to depress the carbonates in combination with the modifying agent, and an inorganic acid from the group consisting of HF, H HCl and H PO to froth flotation at a pH of below 7 and forming a concentrate rich in the pyrochlore mineral and a columbium-lean tailing and collecti ng said concentrate.

6. A process as claimed in claim 5, wherein oxalic acid is used as the modifying agent.

7. A process as claimed in claim 5, wherein hydrofluoric acid is included as amodifying agent in the flotation treatment.

8. A process as claimed in claim 5, wherein calcium chloride is included as a modifying agent in the flotation treatment in promoting the pyrochlore. 

1. A process for beneficiating by froth flotation an ore containing small amounts of the columbIum-bearing mineral pyrochlore and large quantities of gangue materials, including large quantities of carbonates from the group comprising dolomite, ankerite, calcite and siderite, which comprises grinding said ore to a small particle size suitable for separation of the columbium-bearing minerals by froth flotation, subjecting an aqueous pulp of the so-ground ore, in the presence of a cationic collector of the diamine acetate type, having a carbon chain length of 10 to 22 carbon atoms, a dispersing agent acting in combination with the collector, a modifying agent providing a source of free oxalate ions from the group consisting of oxalic acid and oxalate salts and at least one depressant from the group consisting of caustic starch and sodium silicate to depress the carbonates in combination with the modifying agent, to froth flotation at a pH of below 7 and forming a concentrate rich in the columbium-bearing minerals and a columbium-lean tailing and collecting said concentrate.
 2. A process as claimed in claim 1 wherein the diamine acetate collector has a carbon chain length of in the order of 16 to 18 carbon atoms.
 3. A process as claimed in claim 1, wherein calcium chloride is included as a modifying agent in the flotation treatment in promoting the pyrochlore.
 4. A process as claimed in claim 1, wherein the gangue materials include heavy minerals from the group comprising ilmenite, hematite and magnetite and at least one depressant from the group consisting of caustic starch and lactic acid is used to depress the heavy minerals.
 5. A PROCESS FOR BENEFICIATING BY FROTH FLOTATION AN ORE CONTAINING SMALL AMOUNTS OF THE COLUMBIUM-BEARING MINERAL PYROCHLORE AND LARGE QUANTITIES OF GANGUE MATERIALS, INCLUDING LARGE QUANTITIES OF CARBONATES, WHICH COMPRISES GRINDING SAID ORE TO A SMALL PARTICLE SIZE SUITABLE FOR SEPARATION OF THE COLUMBIUM-BEARING MINERALS BY FROTH FLOTATION, SUBJECTING AN AQUEOUS PULP OF THE SO-GROUND ORE, IN THE PRESENCE OF A CATIONIC COLLECTOR OF THE DIAMINE ACETATE TYPE, HAVING A CARBON CHAIN LENGTH OF 10 TO 22 CARBON ATOMS, A DISPERSING AGENT ACTING IN COMBINATION WITH THE COLLECTOR, A MODIFYING AGENT PROVIDING A SOURCE OF FREE OXALATE IONS FROM THE GROUP CONSIST-
 6. A process as claimed in claim 5, wherein oxalic acid is used as the modifying agent.
 7. A process as claimed in claim 5, wherein hydrofluoric acid is included as a modifying agent in the flotation treatment.
 8. A process as claimed in claim 5, wherein calcium chloride is included as a modifying agent in the flotation treatment in promoting the pyrochlore. 